QOD #103 Calculate the POTENTIAL ENERGY of a ball with a mass of 2 kg, sitting on a ledge 3 meters high. (PE=mgh) PE=58.8 Joules 2. Calculate the KINETIC ENERGY of that ball as it falls with a velocity of 15m/s. (KE=0.5mv2) KE = 225 Joules Both units are in Joules!

Work 5-13-14 Work – The amount of energy used as a force moves an object over a distance. Ex. Lifting weights It is not considered work if there is no movement. Work is measured in Joules (J)

Work Equation W = F d Work (J) = Force (N) x distance (m)

Ex1: A student pushes a desk 2 m using a force of 25 N Ex1: A student pushes a desk 2 m using a force of 25 N. How much work does the student do? W = Fd W = 25 N x 2 m W = 50 Joules (J)

Ex2: Jerry drags Tom 3 meters across the floor with a force of 15N Ex2: Jerry drags Tom 3 meters across the floor with a force of 15N. Calculate Jerry’s work. W = Fd W = 15 N x 3 m W = 45 J

Marble Launcher Question: How does the force applied to the marble affect the work done on the marble? Purpose: Calculate work.

IV: force applied to the marble DV: distance marble travels Constants: pressure on lever, size/mass of the marble, Prediction: I think…

The Work Done on a Marble w/ Different Forces Applied Distance (Trial 1) Distance (Trial 2) Distance (Trial 3) Average Distance (m) Work (Joules) 3 N 6 N 9 N 12 N 15 N

Procedures: Jobs: Pull the lever down to the first notch, 3 N. Place the marble in the launcher. Make sure everyone is out of the way & ready! Everyone must wear googles! Push lever & marble will release. Estimate the distance the marble went. Someone must be ready to catch the marble & roll it back to the launcher. Record the distance. Jobs: Marble Launcher Marble catcher Distance reader Recorder

QOD#104 Calculate the amount of work to push a box 20m with a force of 30N. W = Fd W = 30 N x 20 m W = 600 J

Simple Machines Machine – An object that makes doing work easier. Simple Machines – do work using only one movement.

Lever Screw Inclined Plane Pulley Wedge Wheel & Axle Sketch Examples (at least 3) Used for…

What kind of simples machines are the following?

Goonies Rube Goldberg https://www.youtube.com/watch?v=SwaTKYJSDaw Ok-Go! Video http://www.wimp.com/gomachine/

Identify the simple machines in a pair of scissors. QOD#105 Identify the simple machines in a pair of scissors.

Identify the simple machines in a bicycle. Pulley Wheel & axle lever

QOD#106 Calculate the force of an 18kg bowling ball falling off of a building. 2. Calculate the amount of work to push a box 20m with a force of 30N. W = Fd W = 30 N x 20 m W = 600 J 18kg x 9.8m/s² = 176.4 N F = ma

QOD#106 What are the following units for… m/s N km/h north kg J m/s2

5-14-13 QOD#54

Calculating Work Object Action Force (N) Distance (m) Work (J) Book Dragged across floor 50 N 5 m 500 J 1. 2. 3. 4.